1. Field of the Invention
The present invention relates to image motion prediction and compensation, and more particularly, to an image encoding and decoding method and apparatus in which compression efficiency is further improved by filtering motion-compensated image data, thereby reducing errors with respect to original image data.
2. Description of the Related Art
In image compression schemes such as moving picture coding experts group (MPEG)-1, MPEG-2, MPEG-4, H.264/MPEG-4 advanced video coding (AVC), pictures are divided into macro blocks to encode images. Each macro block is subject to inter-prediction or intra-prediction by using the various encoding modes. Thereafter, one of these encoding modes is selected to encode each macro block according to a bit rate required for macro block encoding and according to a distortion degree between a decoded macro block and an original macro block.
In intra-prediction, a prediction value of a current block to be encoded is computed using pixel values of pixels located around the current block, and a difference between the prediction value and an actual pixel value of the current block is encoded. In inter-prediction, a motion vector is generated by searching for a region that is similar to the current block to be encoded in at least one reference picture that precedes or follows the current picture to be encoded, and a differential value between a prediction block generated by motion compensation using the generated motion vector and the current block is encoded.
Conventionally, either intra-prediction or inter-prediction is used to generate a prediction block for a current block, and cost is then computed using a specific cost function. Thereafter, the most inexpensive encoding mode is selected to perform encoding, which leads to improved compression efficiency.
However, to overcome limited transmission bandwidth and to provide high quality images, an image encoding method having an even higher compression efficiency is required.